Roller clutch assemblies are often used in modern vehicle transmissions to serve as passively responding shift timers, thereby smoothing out gear changes. The roller clutch assembly is a functional part of a larger clutch package that includes a central shaft and a surrounding stack of friction disks that engage under hydraulic fluid pressure. The roller clutch assembly is interposed between the central shaft and disk pack, with the inner race splined to the shaft and the outer race splined inside the disk pack. As such, the roller clutch is subjected to a fairly harsh environment in terms of heat, radial and axial loads, friction and wear. In such an environment, a roller clutch is also often exposed to an available supply of pressurized lubricant, which is directed radially outwardly to the disk pack to prevent overheating of the interleaved plates.
The most frequently used type of roller clutch in the transmission clutch package application is the so-called journal block type, which includes a series of plastic bearing blocks that serve to keep the inner and outer clutch races radially spaced and coaxial. A cage generally retains the journal blocks, rollers and springs together as a subassembly that can be easily installed between the races. Typically, however, the cage is not used to retain the clutch races to the rest of the roller clutch as a modular unit or assembly. Instead, the cage and races are generally assembled at the same site where the entire clutch package is assembled. Consequently, the rollers and springs are inevitably exposed for a time, and extra care must be taken to avoid disturbing them. An older type of overrunning roller clutch, often referred to as a leg type roller clutch, does not use journal blocks. Instead, the cam race has an evenly spaced series of projections, so-called legs, machined integrally with it. The ends of the legs are ground to match the pathway, thereby creating bearing surfaces to directly support the pathway race as it overruns. The leg type clutch is generally capable of supporting greater loads, and the journal blocks are eliminated as a separate component. Leg type clutches are also subject to the same drawback of piecemeal race installation and the attendant roller and spring exposure, however.